<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>flat</title>
</head>

<body>
  <script>
    // 将内部子元素进行展开,如传入Infinity则全部展开
    let arr = [1, 2, 3, [1, 2, 3, [4, 5, 6]], [1, 2, [3, 4, 5, [6, 7, 8]]]]
    let arr1 = arr.flat(Infinity)
    console.log(arr1);
  </script>
</body>

</html>